This paper investigates geometrically-nonlinear aeroelastic effects on an industry-level aircraft configuration. Results are obtained via a new approach that uses geometrical information
to compute nonlinear effects and seamlessly integrates with conventional, linear aeroelastic
load packages. The starting point is a generic finite-element model and frequency-domain
aerodynamic influence coefficient matrices, and the resulting system includes control inputs,
longitudinal trim, or gust disturbances in time domain, which can be employed separately or
in combination to obtain a nonlinear dynamic model for loads and stability analysis. The
aeroelastic response of a long range aircraft is studied, highlighting the difference between
linear and nonlinear approaches in the calculations of the aircraft flying equilibrium, dynamic
perturbations, and variations to the flutter boundary. Results justify the need for geometrically nonlinear analysis in the production environment of airplanes with ultra high aspect ratio
wings.